Multi joint mechanical arms, as fluid material conveying devices, have been widely used in fields such as concrete conveying, high-altitude fire-fighting operation and port refueling due to advantages such as good universality, wide operation range and flexible operation, and have become inevitable high-end technical devices in national construction.
A boom system usually comprises a plurality of joint arms, and the large head end of the first joint arm is hinged with a predetermined chassis through a vertical shaft; the large head ends of the other joint arms are hinged with the small head ends of adjacent joint arms through a horizontal hinge shaft; therefore, a plurality of joint arms are sequentially hinged through the horizontal hinge shaft, and the joint arm at the distal end extends outwards and is called a distal end joint arm, and the outer end of the distal end joint arm forms a boom system distal end; driving mechanisms such as hydraulic cylinders are provided between adjacent joint arms, so that the angles between adjacent joint arms generate a predetermined change, which changes the position of the boom system distal end so as to convey materials or articles to a predetermined position.
As a mechanical arm is affected by dead weight and construction postures, a rigid flexible coupling mechanical arm deforms in a complex way, which seriously affects its distal end positioning precision. To obtain the postures of the mechanical arm and achieve precise positioning of the distal end of the mechanical arm, usually a proper coordinate system is established in a control system, and the coordinate parameters of the coordinate system are used to determine the positions of the hinged points of the joint arms of the mechanical arm, and the deformations of respective joint arms are considered to finally determine the actual distal end position of the mechanical arm, and the coordinate parameters of the distal end position are called position parameters.
In addition, during using the boom system to work, each joint arm bears corresponding load, and generates corresponding deformation; the accumulation of deformations of a plurality of joint arms will result in a large deviation between the position parameters of the boom system distal end and target position parameters.
To reduce the deviation of the position parameters of the boom system distal end rendered by the deformation of the mechanical arm, one manner for obtaining the distal end position parameters in the related art is to use two dip angle sensors to obtain the deformation amounts of corresponding joint arms and then correct the position parameters of the joint arms according to the deformation amounts. Although this manner can improve the accuracy of the boom system distal end position parameters, due to the restriction by the measuring precision of the dip angle sensors, the deviation between the position parameters of the boom system distal end and the target position parameters is still large, and the demands of accurate positioning and control on the boom system distal end cannot be met.
Therefore, how to improve the accuracy of the boom system distal end position parameters is still a technical problem to be solved by one skilled in the art.